This chapter is promulgated pursuant to chapter 90.54 RCW (Water Resources Act of 1971), chapter 90.22 RCW (minimum water flows and levels), and in accordance with chapter 173-500 WAC (water resource management program).

The purpose of this chapter is to retain perennial rivers, streams, and lakes in Lake Washington drainages with instream flows and levels necessary to provide for preservation of wildlife, fish, scenic, aesthetic and other environmental values, navigational values, and to preserve water quality.

(1) The department of ecology has determined that additional diversions of water from the Lake Washington drainage system would deplete instream flows and lake levels required to support the uses described in WAC 173-508-020. Therefore, lakes and streams contributing to the Lake Washington drainage above the Hiram M. Chittenden Locks, excluding the Cedar River drainage, shall be closed to further consumptive appropriations. Regulation to protect instream flows in the Cedar River and its tributaries shall be undertaken pursuant to WAC 173-508-060.

(2) WAC 173-508-040—Table 1, includes specific named and unnamed surface water sources in water resource inventory area 8 with restrictions indicated. All tributaries in the Lake Washington drainage not specifically included in Table 1 are closed.

In future permitting actions relating to groundwater withdrawals, the natural interrelationship of surface and groundwaters shall be fully considered in water allocation decisions to assure compliance with the intent of this chapter.

(1) The instream flows established in this section apply to waters of the Cedar River and affect the entire watershed drained by the Cedar River including all tributaries thereto.

(2) Instream flows established in this section shall be measured at the existing U.S. Geological Survey gaging station No. 12.1190.00 on the Cedar River at Renton, Washington.

(3) Except as provided herein (critical year flows), water flows in the Cedar River and tributaries thereto shall, to the extent depletion under existing rights and natural flow conditions permit, be maintained throughout each year at levels which, during the time periods designated, do not fall below the following measurements:

(a) Normal Year Flow

Normal year flows must be maintained at all times unless a critical condition is declared by the director. If natural Cedar River flows fall below the 1 in 10 year Cedar River flow frequency, the director, or his designee, may authorize flows below the normal year flows, but not lower than the critical year flow except where a declaration of overriding considerations of public interest is made by the director. All requests to deplete below the established instream flow level will be considered on a case-by-case basis.

Critical year flows represent flows below which the department believes substantial damage to instream values will occur. Critical year flows are expected to be met unless natural Cedar River flows fall below the one in fifty year Cedar River flow frequency.

No water rights to divert or store public surface waters of the Cedar-Sammamish basin WRIA 8 shall hereafter be granted which shall conflict with the instream flows and closures established in this chapter. Future rights for nonconsumptive uses may be granted under the provisions of this chapter.

(1) Nothing in this chapter shall affect any existing water rights, riparian, appropriative, or otherwise, existing on the effective date of this chapter; nor shall it affect existing rights relating to the operation of any navigation, hydroelectric or water storage reservoir or related facilities.

(2) Domestic inhouse use for a single residence and stock watering, except that related to feedlots, shall be exempt from this chapter.

In enforcement of this chapter, the department of ecology may impose such sanctions as appropriate under authorities vested in it, including but not limited to the issuance of regulatory orders under RCW 43.27A.190 and civil penalties under RCW 90.03.600.

All final written decisions of the department of ecology pertaining to permits, regulatory orders, and related decisions made pursuant to this chapter shall be subject to review by the pollution control hearings board in accordance with chapter 43.21B RCW.

The department of ecology shall initiate a review of the rules established in this chapter whenever new information, changing conditions, or statutory modifications make it necessary to consider revisions.